1. Field of the Invention
The present invention relates to a disk drive apparatus for reproducing or recording from/on a rotating disk, and also to a motor usable at least in the disk drive apparatus.
2. Description of the Related Art
In recent years, a disk drive apparatus such as an optical disk drive apparatus (DVD, CD, and so on) and a magnetic disk drive apparatus (HDD, FDD, and so on) includes a motor that electronically alters current paths to windings by using plural transistors.
FIG. 40 shows such a prior art motor usable in the disk drive apparatus, the operation of which will be described concisely here.
A rotor 2011 has a field part formed by a permanent magnet. According to the rotation of the rotor 2011, a position detecting block 2041 generates two pairs of three-phase voltage signals K1, K2, K3 and K4, K5, K6. A first distributing block 2042 generates three-phase lower conduction control signals L1, L2 and L3 corresponding to the voltage signals K1, K2 and K3, and controls the conduction of lower NPN-type power transistors 2021, 2022 and 2023. A second distributing block 2043 generates three-phase upper conduction control signals M1, M2 and M3 corresponding to the voltage signals K4, K5 and K6, and controls the conduction of upper PNP-type power transistors 2025, 2026 an 2027. Consequently, three-phase drive voltages are supplied to three-phase windings 2012, 2013 and 2014.
There are various problems in the above-mentioned prior art.
In the prior art configuration, the emitter-collector voltages of the NPN-type power transistors 2021, 2022 and 2023 and the PNP-type power transistors 2025, 2026 and 2027 are controlled in analogue fashion, thereby supplying drive currents of necessary amplitude to the windings 2012, 2013 and 2014. Consequently, the residual voltage drop across the power transistor in activated period becomes large, and the product of this residual voltage drop and the conducted current of the power transistor causes a large power loss. Since the drive currents to the windings have been large, the sum power loss has been extremely large. As a result, the disk drive apparatus including the motor produces a large power consumption and thus has a very low power efficiency.
In order to reduce the manufacturing cost, it is effective to integrate transistors, resistors, and the like on a single chip as an IC. However, a power loss and a heat generation of the power transistors are too large to integrate power transistors with other transistors and resisters into an IC. Especially, since the drive currents to the windings are large, the IC is likely to confront with a thermal breakdown caused by the heat generation from those power transistors. If a radiating plate is provided to the IC in order to prevent such a thermal breakdown, then the cost and the size will be increased greatly.
In recent years, there is a strong demand for a disk drive apparatus to reduce its vibration and an acoustic noise of the rotating disk in order to carry out a higher density reproducing and/or recording from/on such disks. In the prior art configuration, when a power transistor is changed over abruptly, a spike voltage is generated in a winding, thereby pulsating the drive currents. Therefore, the generated force is pulsated and a large vibration of the disk occurs, thereby producing a large acoustic noise from the disk.
In optical disk drive apparatus such as DVD-ROM and CD-ROM and magnetic disk drive apparatus such as HDD and FDD, the vibration of the disk produces a jitter of the rotational speed of the disk so that a bit error rate of the signal reproduced from the disk would become worse. The acoustic noise of the disk will interfere and disturb enjoyment of an audio-visual movie reproduced from the disk, because the acoustic noise is an audible noise. Further, in a disk drive apparatus using a recordable disk, a recording and/or reproducing mechanism of the disk drive apparatus is strongly demanded to reduce its power consumption because the recordable disk is easily affected to degrade the recording characteristics by heat or high temperature due to high power consumption.
It has been strongly desired to develop a disk drive apparatus and/or a motor in which each of or all of these problems are solved.
It is therefore an object of the present invention to solve the above-mentioned problems, respectively or concurrently and provide a disk drive apparatus and/or a motor that has the configuration suitable for reducing the vibration, the acoustic noise, and the power consumption.